5 sheets of 1/8" aluminum is what I should have used but I made a few mistakes along the way. I used some left over aluminum for the bow deck which was .090. With the expanding foam under it it is rock solid. It was a tough to weld the .090 to the 1/8"
Aluminum 5 sheets 60x120x.125- $920.00
Consumables for the welder and grinding wheels - $145.00
Foam 4lb Density two part 25lbs - $258.00
3/8" plywood for floor plus pink foam board-
Hatch covers from Cabellas
Paint / Deck rubberized coating
Misc screws and parts
Cost as a minimum is listed above. I could have saved money by building all of my own covers, I will do this on the next one. It was faster just to buy them but the covers are pricey from Cabellas or West Marine.
I would go with aluminum in the next one for the floor instead of the plywood, and use the Max-4 Pads from Styx River for comfort and noise reduction.
I used 5'x10' sheets because I could burn them on the plasma machine and handle them after hours by myself. Not worried about strength (they don't build ocean liners out of one piece of metal) but there is a slight weld ripple or seam that is noticeable where I pieced it together.
I would build a jig or strong-back for any boat in the future and recheck all dimensions prior to burning or cutting out of the parts.
Hours building - about 48 not including just sitting and staring at it, planning the next move.
and I still have a few odds and ends.